THE entire 2011 UK census database has been stolen by hackers and will be made public online, it was claimed today.

Ryan Cleary, an alleged member of notorious hacker group LulzSec, was arrested in Essex this morning by specialist cyber-crime officers from Scotland Yard.

The 19-year-old was taken to a central London police station and remains in custody on suspicion of Computer Misuse Act and Fraud Act offences.

The dawn swoop, launched in collaboration with the US FBI, recovered a “significant amount of material” and was triggered by internet claims that the 2011 census database had been stolen and would be published in full.

A LulzSec operative said. “We have blissfully obtained records of every single citizen who gave their records to the security-illiterate UK government for the 2011 census.

“We're keeping them under lock and key though... so don't worry about your privacy (...until we finish re-formatting them for release).”

The posting was uploaded to the website Pastebin.com, which has previously been used by LulzSec to publicise its attacks. It said the database will be published via The Pirate Bay, a file sharing website.

The Office of National Statistics said it was investigating the latest claims and added: “We are aware of the suggestion that census data has been accessed. We are working with our security advisers and contractors to establish whether there is any substance to this.”

Security experts will be taking the threat seriously. LulzSec hackers have previously successfully struck at high profile organisations including the CIA, Sony, the US Senate, the NHS, the Serious Organised Crime Agency.